We have continued to explore the mechanism of acute lung disease in newborn, children, and adults, and in devising methods and devices to treat those disease states through the use of extracorporeal perfusion systems. Methods in the prevention, and treatment, are based on recognition that carbon dioxide removal is controlled by pulmonary ventilation, while oxygen transport through the lungs may proceed even in total apnea (apneic oxygenation). In still ongoing experiments we have proven the great dangers inherent to positive pressure ventilation, at peak pressures greater than 40 cm. H2O, using animal models. Healthy lungs so subjected to elevated airway pressures for 12-48 hours developed massive atelectasis and decreased lung compliance. The minimum surface tension of saline lung wash was highly abnormal, indicating damage at the cellular level. Hence, those studies have shown that conventional mechanical pulmonary ventilation leads to iatrogenic lung damage, once high airways pressures have developed. We propose, that prior to reaching high airways pressures, the patient be placed on the extracorporeal membrane lung bypass for carbon dioxide removal. This will immediately obviate the need for elevated airways pressures and allow the lungs to heal. We are improving on our extracorporeal perfusion system through the design of a singly catheter bypass method. Only one venous catheter is required for access to blood if blood flow in the catheter (from and to) is directed in a programmed fashion, similar to the way single needle hemodialysis is practiced. Bypass can hence begin immediately after one single catheter insertion. We are developing an integrated perfusion system for both extracorporeal CO2 removal, and/or cardiac assist, using pneumatically controlled pumps. Such a system is very compact, has good flow patterns, and can be ready to commence bypass within minutes. Through special design, the assembly of the system is particularly easy easy and could be designed to come as a completely disposable system.